%!TEX TS-program = xelatex
%!TEX encoding = UTF-8 Unicode

\documentclass[11pt,tikz,border=1]{standalone}
\usetikzlibrary{calc,positioning}
\usepackage{pgfplots}

\usepackage[default]{cjkfonts}

\begin{document}

\begin{tikzpicture}
  
    \begin{axis}[
        axis lines=left,
        xscale=1.5,
%        xlabel=$Z$,
        xtick distance=1,
        ytick distance=0.05,
        xtick={-4,-3,-2,-1,0,1,2,3,4},
        ytick={0.00,0.05,0.10,0.15,0.20,0.25},
%        xmax=5.1,
        ymax=0.255,
%        title={S 型函数的导数},
        declare function={
          sigmoid(\x) = 1 / (1 + exp(-\x));
          f(\x) = sigmoid(\x) * (1 - sigmoid(\x));
        }
      ]
      \addplot[
        blue,
        thick,
        domain=-5:5,
        samples=201
      ] {
        f(x)
      };
    \end{axis}    

    \node [above] at (5, 6) {S 型函数的导数};
    \node at (5, -1) {$Z$};
  
\end{tikzpicture} 

\end{document}
